The invention relates to a hybrid vehicle optionally driven by an electrical machine, which can be supplied with power from a galvanic cell or which, during a generating operation, supplies the galvanic cell with power, and by an internal-combustion engine which can be supplied with a combustible liquid from a tank. In these types of hybrid vehicles, an activated carbon canister, as an intermediate storage device for hydrocarbons, is also installed between the fuel tank and the environment in the tank ventilation system. This intermediate storage device, controlled by way of the electronic system of the engine, is conventionally regenerated by an air stream. In this case, air is guided over the carbon particles of the activated carbon canister which are occupied by hydrocarbons, whereby the hydrocarbons are detached and are conveyed to the internal-combustion engine by way of the air stream. This air stream from the activated carbon canister charged with hydrocarbons is admixed to the combustion air and is burnt.
U.S. Pat. No. 7,114,492 describes a motor vehicle, in the case of which, in the tank ventilation system, a washer for short-chain hydrocarbons on the output side of the activated carbon canister is provided in the proximity of the exhaust system of the vehicle in order to heat the washer.
International patent document WO 2006/008301 relates to the heating of the scavenging air flow for an activated carbon canister of a tank ventilation system by use of a heat exchanger on the exhaust system of the motor vehicle. In this case, the exhaust system and the tank are arranged in an adjacent manner, but are thermally insulated from one another.
German patent document DE 4140090 relates to an activated carbon canister for the tank ventilation system of a motor vehicle, which is arranged between the exhaust system and the fuel tank of the motor vehicle.
It is an object of the invention to further develop the hybrid vehicle of the above-mentioned type and, particularly, to improve its tank ventilation system.
This object is achieved by providing a hybrid vehicle optionally drivable by an electrical machine or an internal-combustion engine. The electrical machine can be supplied with power from a galvanic cell or, during a generating operation, supplies the galvanic cell with power. The internal-combustion engine is supplied with a combustible liquid from a fuel tank. An activated carbon canister is assigned to the fuel tank for collecting vapors of the combustible liquid. The activated carbon canister is positioned in an area of the galvanic cell, and is connectable, as required, with an intake system of the internal-combustion engine for carrying out a scavenging. Advantageous developments and further developments of the invention are described herein.
According to the invention, the activated carbon canister assigned to the fuel tank of an internal-combustion engine, for collecting fuel vapors, is positioned in the area of the galvanic cell from which the electrical machine of the hybrid vehicle can be supplied with current in order to operate the latter as an electric motor or which is supplied with current during the generating operation of the electrical machine. As a result of the positioning of the activated carbon canister according to the invention, the waste heat occurring at the galvanic cell can be used for heating the activated carbon canister. In this case, the invention utilizes the recognition that, in the case of a hybrid vehicle, a lower heat entry or a lower generating of vapor occurs in the fuel tank. This is a result of the fact that, at least at times, the internal-combustion engine is out of operation.
The electric delivery device (fuel pump), which causes an entry of heat into the fuel, is therefore less frequently in operation in the case of a hybrid vehicle. In addition, when there is a return flow, hot fuel is less frequently returned into the fuel tank. As a result of the correspondingly lower fuel-vapor quantity in the case of a hybrid vehicle compared with a conventional motor vehicle, the amount of fuel vapors to be absorbed by the assigned activated carbon canister is also lower. However, it should also be taken into account here that, because of the only temporarily operated internal-combustion engine, the scavenging phases of the activated carbon canister also turn out to be less frequent. Summarizing, although the activated carbon canister in a hybrid vehicle has to adsorb less fuel vapor in comparison with a conventional vehicle, it is also scavenged less frequently. As a result, the required adsorption in the case of an activated carbon canister of a hybrid vehicle is lower than in the case of a conventional vehicle. Thus, the provided heating of the activated carbon canister, as a result of the placing provided according to the invention in the area of the galvanic cell, specifically does not lead to a reduced efficiency of the tank ventilation. On the contrary, the increased temperature results in an improved regeneration of the adsorbed hydrocarbons during a scavenging operation, whereby the latter does not have to be carried out as frequently. In other words, according to the invention, the equilibrium between adsorption and regeneration of the activated carbon canister is shifted in that the temperature of the activated carbon canister is raised. In this case, as a result of a corresponding placing of the activated carbon canister, a desired state of equilibrium is adjusted corresponding to a defined (average) temperature.
It is advantageous to provide the galvanic cell as a high-voltage battery pack, particularly of the nickel-metal-hydride (NiMH) or lithium-ion type. On the one hand, these are proven and efficient suppliers of power for an electrical machine of the hybrid vehicle. On the other hand, they supply a corresponding waste heat, whereby the correspondingly positioned activated carbon canister is heated and its regeneration is thereby improved. Naturally, other types of galvanic cells can also be provided, such as fuel cells and lead accumulators. Furthermore, when several galvanic cells are used in the hybrid vehicle, a positioning of the activated carbon canister on a galvanic cell favorable, for example, with respect to installation space aspects may be provided.
The galvanic cell and the activated carbon canister are, preferably, provided in the area of the trunk recess or space of the hybrid vehicle. As a result of the corresponding weight of the galvanic cell, a low center of gravity of the vehicle is thereby obtained. In addition, in this area, sufficient installation space is normally available. In the case of this type of configuration, another advantage is obtained by the arrangement according to the invention. In that the relatively voluminous activated carbon canister is positioned correspondingly, it can be used as a mechanical guard shield for the relatively susceptible galvanic cell. By a corresponding placement, the activated carbon canister can, for example, absorb energies in the event of a crash of the hybrid vehicle and/or can be used as a stone guard.
It is particularly advantageous to configure the exhaust gas system of the internal-combustion engine of the hybrid vehicle such that the activated carbon canister is positioned between the galvanic cell and a part of the exhaust system. For example, a catalytic converter, a muffler, and/or a pipe of the exhaust system may extend in the proximity of the activated carbon canister. As a result of the additional waste heat of the exhaust system, this leads to a further temperature increase and thus a correspondingly improved regeneration in the activated carbon canister.
A favorable fastening possibility of the activated carbon canister is obtained when the canister is fastened to a covering of the galvanic cell. The utilization of such coverings or fastenings eliminates the necessity of providing additional fastening possibilities for the activated carbon canister. This permits a particularly material-saving construction.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.